X-ray absorption and x-ray magnetic circular dichroism in bulk and thin films of ferrimagnetic GdTiO3

Perovskite rare-earth titanates are prototypical Mott insulators in which Ti3+ ions with 3d(1) electronic configuration exhibit ferromagnetic or antiferromagnetic spin order, depending on the rare-earth size. This peculiar magnetic behavior has, however, been barely studied with element-specific probes, either in bulk or in thin films. The recent finding of fingerprints of ferromagnetism in two-dimensional electron gases at oxide interfaces involving rare-earth titanates has produced a surge of the interest in these complex materials. Harnessing the interfacial magnetic states in these heterostructures calls for a better understanding of their insufficiently explored magnetic states in bulk and especially in thin film form. In this paper, we combine high-resolution transmission electron microscopy with x-ray absorption spectroscopy and x-ray magnetic circular dichroism (XMCD) to determine the structural, electronic, and magnetic structure of GdTiO3 in bulk and thin film form. In both cases, we find that the sample surface is strongly overoxidized but a few nm below, Ti is mostly 3+ and shows a large XMCD. We provide evidence for the ferrimagnetic nature of GdTiO3 with antialigned Gd and Ti sublattices and show that, just as in antiferromagnetic LaTiO3 or ferromagnetic YTiO3, Ti carries no orbital moment.

Automated summary

This study investigates the magnetic behavior of rare-earth titanates, revealing the ferrimagnetic nature of GdTiO3 and providing insights into its structural and electronic properties in bulk and thin film form. The research sheds light on the insufficiently explored magnetic states of these complex materials, particularly at oxide interfaces.